textproduct: Quad Cities

KEY MESSAGES

- A storm system will pass through the area today into Wednesday morning, bringing the chance for showers and thunderstorms. A few storms may be strong to severe, but confidence is low.

- Another stretch of quieter weather returns late in the week and into the weekend, with limited precipitation chances.

SHORT TERM /THROUGH WEDNESDAY/

Issued at 133 AM CDT Tue Aug 18 2026

Upper level northwest flow will guide another shortwave trof through the area tonight, with weak bouts of energy passing overhead ahead of it through the daytime. A 20-30 KT LLJ will supply the necessary moisture to favor the development of showers and embedded thunderstorms today. As we have seen in the recent forecast packages, the showery activity continues to trend earlier on onset for our area. We are now looking at the potential for showers with some embedded thunder moving into our northwest as early as mid morning. Overall, forcing over the area will be lacking, which should limit overall impacts as this moves through the area this morning and early afternoon. As the main upper wave and associated cold front approach the area this evening/tonight, there will be the chance for redevelopment of showers/storms. Although, confidence continues to decrease on this occurring, as short term guidance continues to trend more dry. This late afternoon and evening development will be conditional on if we can destabilize the environment enough in the afternoon. Overall forcing seems to remain weaker though, which should help limit convective coverage to isolated- scattered along the cold front. If we manage to redevelop storms, the environment would favor a few strong to severe storms, with the SPC highlighting our whole area in a Marginal Risk, level 1/5, for severe weather. Primary threats with any storm will be damaging winds, with hail secondary.

The cold front will be slow to move out of the area tonight, with it reaching the Interstate 80 corrider around sunset this evening. This would leave areas north of the interstate mostly dry through tonight, with the chance for isolated-scattered storms remaining for areas south of Interstate 80 through the night. By sunrise on Wednesday, the cold front will have exited the area, with only a few post-frontal showers remaining for the Wednesday morning commute along/south of Highway 34.

LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/

Issued at 133 AM CDT Tue Aug 18 2026

We may continue to see some residual showers early Wednesday morning, but should largely exit the area by mid morning. Post- frontal airmass will kick in Wednesday, with light northeasterly winds and decreasing cloud cover. High pressure will approach the area later on Wednesday, tracking through the Great Lakes Region on Thursday. This will lead to a largely quiet second half of the week, with mostly dry conditions and temperatures slightly cooler. Weak northwesterly flow will remain overhead, with a few weak impulses in the flow. Although, with low moisture and lacking return flow, we are not expecting much rain for the rest of the week. If we manage to see any showers from these passing waves, they will largely be in the form of isolated instability showers. Guidance continues to favor the better chances for these showers on Friday, with 20-40% PoPs. Due to low moisture content, accumulations would be low with these showers, where most locations are likely to remain dry at this time. In the end, a much needed stretch of mostly-dry weather will be seen late week and through the weekend, with comfortable humidity and temperatures largely in the upper 70s.

AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/

Issued at 1221 AM CDT Tue Aug 18 2026

VFR conditions will prevail through the nighttime hours, with the chance for showers and storms increasing after 10z from northwest to southeast. Overall, confidence is low in this activity. Thus, opted to message through PROB30 groups at this time, with main impacts being reduced vis in showers. Otherwise, there will be more chances for showers/storms after 18z, but confidence is low on timing and coverage. Opted to leave mention out of the TAFs at this time. Winds will remain light and variable through the start of the TAF period, becoming southwesterly around 10 KTs after 12z.

DVN WATCHES/WARNINGS/ADVISORIES

IA...None. IL...None. MO...None.